This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 6 |
| 5 | 32 |
| 6 | 190 |
| 7 | 1332 |
| 8 | 10654 |
| 9 | 95888 |
| 10 | 958878 |
| 11 | 10547660 |
| 12 | 126571918 |
| 13 | 1645434936 |
| 14 | 23036089102 |
| 15 | 345541336532 |
| 16 | 5528661384510 |
| 17 | 93987243536672 |
| 18 | 1691770383660094 |
| 19 | 32143637289541788 |
| 20 | 642872745790835758 |
| 21 | 13500327661607550920 |
| 22 | 297007208555366120238 |